This is the page where all the genres used in genre tagging are listed. A useful page is Special:GenreParserInfo, which shows the internals of how this page is parsed, and any errors that occurred during parsing.
The parser will ignore all lines on this page that do not start with * or #. However, any list so started does not need to be continuous.
The valid characters in the list are A-Z, a-z, 0-9, comma, (), dash, period, space.
All lines pertaining to category hierarchy must start with *. The number of asterisks shows the level of depth.
Note: Any of the categories below may be subject to change at any time
Instrumental categories are now sub-divided into Keyboard, Chamber-Instrumental, Orchestral and Vocal
These sections are actually now part of this page, and must be defined if you want them to appear on the CategoryWalker page. They will adhere to the order of root nodes in the hierarchy (you can order them however you like within the tree, but they must stay root nodes [i.e. depth of 1]).
A category does NOT have to exist (in fact, probably will not exist) before being defined in this hierarchy. This hierarchy will create categories on the fly.
Note: The root "category" (e.g. "Work Types") is NOT included as a category (see my note below in the Tags section), and using a root category in a tag will result in an "empty tag" error, meaning that there are no categories associated with the tag.
The root category exists as a separator used by CategoryWalker, not as part of the tagging system. It is not a real "category", unlike its children.
All tags should refer to a category defined above in the hierarchy. If a nonexistent category (i.e. not defined above) is used, a warning is thrown (via the info page above). All categories used in tags will automatically include every lineage (i.e. its parents) EXCEPT the root, which exists for other purposes (i.e. Special:CategoryWalker).
All lines defining tags must start with #. Use the parser info page linked above to see how the parser resolves the tags into actual categories.
To use a tag on a work page, simply add "|Tags=" followed by the tags separated by semi-colons to the end of the General Information section of the page.
Simply replace instances of the category in the tag list. There is nothing the parser will use outside of this page, so categories can be created and destroyed purely on this page.
Pages will only update (real) category links on two conditions: (a) a page purge/parse (i.e. when &action=purge is called, or the page cache expires after the period [3 days currently] and a view occurs), and (b) page moves. Most notably, this means that (a) (real) categories will not get updated as soon as this page is changed, but rather over the course of a few days, and (b) some pages that are never viewed (i.e. not viewed after 3 days) will never have their links updated.
This is a known issue, and is the way it is for performance reasons. This may be alleviated (or fixed entirely) in the future, but is not an urgent issue because I can rebuild the category links for all pages at any time.
The old genres have now been removed (June 2010).